title: In vivo and in vitro imaging of I₂ imidazoline receptors in the monkey brain.
abstract: I₂ imidazoline receptors (I₂Rs) are associated with depression, Alzheimer's disease, and Huntington's disease. However, in vivo imaging of I₂Rs in the monkey brain has not been reported until now. We performed in vitro and in vivo imaging of (I₂Rs) in the monkey brain using ¹¹C-labeled 2-(3-fluoro-4-tolyl)-4,5-dihydro-1H-imidazole ([¹¹C]FTIMD) which has high and selective affinity of I₂Rs. In an auto-radiography (ARG) study, the distribution pattern of [¹¹C]FTIMD in the monkey brain was similar to that of [³H]idazoxan binging to I₂Rs in the human brain, which was previously described. The specific binding of [¹¹C]FTIMD accounted for >97% of total binding in brain regions existing I₂ Rs. In positron emission tomography (PET) studies, the radioactivity was accumulated in brain regions existing I₂Rs ligand BU224, the accumulated radioactivity was decreased to approximately 66%-75% of the baseline measurement at 15-45 min after injection of [¹¹C]FTIMD. These results suggest that [¹¹C]FTIMD shows the specific-binging to I₂Rs in the monkey brain as depicted by PET and ARG. We performed the first in vivo imaging of I₂Rs using [¹¹C]FTIMD in the monkey brain.
authors.affiliation: Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan. kawamur@nirs.go.jp
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kawamura
authors.forename: Jun
authors.initials: J
authors.lastname: Maeda
authors.forename: Akiko
authors.initials: A
authors.lastname: Hatori
authors.forename: Takashi
authors.initials: T
authors.lastname: Okauchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagai
authors.forename: Makoto
authors.initials: M
authors.lastname: Higuchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suhara
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Fukumura
authors.forename: Ming-Rong
authors.initials: MR
authors.lastname: Zhang
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000493:pharmacokinetics; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D001931:Brain Mapping; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D019329:Idazoxan / Q000493:pharmacokinetics; D007093:Imidazoles / Q000493:pharmacokinetics; D054755:Imidazoline Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D066298:In Vitro Techniques; D008253:Macaca mulatta; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods; D011485:Protein Binding / Q000187:drug effects; D013997:Time Factors
chemical_list: C552745:2-(3-fluorotolyl)-4,5-dihydro-1H-imidazole; D058669:Adrenergic alpha-2 Receptor Antagonists; C105826:BU 224; D002250:Carbon Radioisotopes; D007093:Imidazoles; D054755:Imidazoline Receptors; C487767:imidazoline receptor 2; D019329:Idazoxan